One in seven shops on the high street is now boarded up, the victims of a faltering economy and the long-term trends towards online and out-of-town shopping, according to a report published on Thursday.

In the most depressed locations, the vacancy rate is one in three shops, with the title of worst-hit small town going to Leigh Park in Havant, near Portsmouth.

Leigh Park has overtaken Margate, which had the worst vacancy rate when the research was last compiled. But there are also some surprises. Wandsworth, in south London, home of bonus-bracket bankers, has slipped on to the list of the 10 small centres with the highest levels of shop vacancies.

Among the largest centres, Stockport and Blackpool top the list, with vacancy rates at more than 25%, while among medium-sized centres, rates are nearly 30% in Dudley and West Bromwich.

The survey, by the Local Data Company, highlights the scale of the challenge facing Mary Portas, who has been given the task of drafting a plan to rejuvenate Britain's high streets. She is due to report to the government in the autumn.

Consumers have been deserting high streets in recent years, preferring to drive to out-of-town shopping malls, and the LDC research says that the big property companies that own them are continuing to do well while others suffer.

But shoppers have also been curbing spending, as many face pay freezes or job losses, and inflation continues to run ahead.

For retailers, the only crumb of comfort in the report is that the growth in high street vacancy rates appears to have stalled: the first half of 2011 was only as bad as – rather than worse than – 2010.

"This report shows how fragile the British high street is in parts of the country," said Matthew Hopkinson, the LDC's director. "The pressures it faces are increasing and therefore one needs to be realistic in one's approach to each and every one of these towns if they are all to have a future.

"The stark reality is that Great Britain has too many shops in the wrong locations and of the wrong size. The diversity of shop vacancy rates is clear evidence that a local approach is required that ties in with consumer needs and the realities of modern retailing. The market still has significant corrections ahead and the impact of these will vary significantly according to location."

Those left behind by the move to out-of-town malls include many northern centres, where retail vacancy rates are higher. The north-south divide is also widening. The north-west and the north-east have the highest vacancy rates, while the south-east and London have the lowest. According to the LDC, town centre vacancy rates have surged, from just over 5% at the end of 2008 to 14.5% today as one in seven shops pull down the shutters.

Experts differ on what ought to be done. Landlords argue that out-of-town centres should not be punished for being successful. "We must also accept that some secondary retail units are no longer viable and plan their transition to other uses. Simply hurting successful retailing to level the playing field is not the solution. We must find new ways to get people on to our high streets and in our local shops," said Liz Pearce, the chief executive of the British Property Federation.

Those with a major stake in high streets take a different view, however.

"For every one square foot of new retail space planned in town centres, four square feet are planned out of town," said Shane Brennan, public affairs director for the Association of Convenience Stores. "The ability to build stores outside towns has been made possible by a combination of confused and poorly applied planning rules, the power of developers, and weakness of local councils. Unless we see urgent action our high streets will be lost to a final wave of out-of-town retail construction that threatens to remove retail from the heart of our communities."

John Pal, senior lecturer in retailing at Manchester Business School, suggested there was just too much retail space – just days before another 1.9m sq ft of shopping space opens next to the Olympic Stadium in east London.

"The downturn in consumer confidence means that there are too many shops chasing too few customers. Whilst some retailers, such as Woolworths and Focus DIY, have gone out of business and had their best sites snapped up by competitors, other retailers have been closing stores in a bid to remain profitable. The challenge, for those with a stake in smaller centres in particular, is how to remain viable for retailers and attractive for customers."

Chuka Umunna MP, the shadow minister for small business and enterprise, called for a cut in the rate of VAT to help struggling high streets. "These new figures on shop vacancy rates demonstrate how a lack of confidence in the economy, coupled with the VAT hike and the squeeze on family incomes, is hitting the high street.

"The Tory-led government needs to take urgent action to help retailers and stop our high streets stagnating," he said. "A temporary cut in VAT would help consumers and businesses now, kick-start the stalled recovery and so help us get the deficit down."